JP 2005-348193 A (PTL 1) discloses an electronic device, in particular an acoustic apparatus such as a mobile phone, that transmits air-conducted sound and vibration sound to a user. In PTL 1, the air-conducted sound refers to a sound transmitted to the user's auditory nerve when the eardrum vibrates upon vibration of air, caused by a vibrating object, reaching the eardrum through the external ear canal. In PTL 1, the vibration sound refers to sound that is transmitted to the user's auditory nerve through a portion of the user's body, such as the cartilage of the outer ear, that is in contact with a vibrating object.
In the telephone disclosed in PTL 1, a rectangular plate-shaped vibrating body, composed of a piezoelectric bimorph and a flexible substance, is attached to an outer surface of a housing via an elastic member. PTL 1 also discloses that when voltage is applied to the piezoelectric element bimorph in the vibrating body, the piezoelectric material expands and contracts in the longitudinal direction, causing the vibrating body to undergo bending vibration. Air-conducted sound and vibration sound are then transmitted to the user when the user brings the vibrating body in contact with the auricle.